Range-finder



5 Sheets-Sheet 1.

(No Model.)

A. BARR 8v W. STROUD.

RANGE FINDER No. 583,243. Patented May 25,1897

'5 Sheets-Sheet 2.

(No Model.)

A. BARR & W. STROUD. RANGE FINDER.

No. 588,243. Patented May 25,1897.

(No Model!) 5 Sheets-Sheet 3. A. BARR & W. STROUD.

RANGE FINDER No. 583,243. Patented May 25,1897.

5 SheetsSheet 4.

(No Model.)

A. BARR & W. STROUD.

RANGE FINDER.

No. 583,243. Patented May 25,1897.

(No Model.)

A. BARR & W. STROUD;

RANGE FINDER.

No. 583,243. Patented May 25. 1897 EE F FIE 22- Flt-1.2 5.

5 Sheets-Sheet 5.

UNITED STATES PATENT OEEIcE.

ARCHIBALD BARR, OF GLASGO\V, SCOTLAND, AND lVILLlAM STROUD, OF

LEEDS, ENGLAND.

RANGE-FINDER.

SPECIFICATION forming part of Letters Patent No. 583,243, dated May 25,1897'.

Application filed January 19,1895. Serial No. 535,567. (No model.)Patented in England July 12,1893,N0.18,507; in France June 23, 1894, No.239,528; in Italy July 27, 1894, No. 36,926, and in Belgium August 8,1894,N0.111,389.

To all 1071/0771 21/ 771/051 concern:

Be it known that we, ARCHIBALD BARR, a resident of Glasgow, Scotland,and \VILLIAM STROUD, a resident of Leeds, England, subjects of the Queenof Great Britain and Ireland, have invented Improvements in Range-Finders, of which the following is a specification.

This invention is embodied in patents in the following countries: GreatBritain, No. 13,507, dated July 12, 1893; France, No. 239,528, datedJune 28,189l; Italy, No. 30,026, dated July27, 1894:, and Belgium, No.111,339, dated August 8, 18%.

This invention relates to improvements in single-observer range-findersand the object is to construct such instruments so that they shall givemore accurate means for determinin g the ranges or distances of objects.

Our invention is an improvement in that construction of range-finderdescribed, shown, and claimed in Letters Patent No. 567,675, issued tous on the 15th day of September, 1890.

In the drawings, Figure 1 is a side elevation of our improved ran ge-iinder, the casing being shown in section. Fi 2 is a top view looking atright angles to that shown in Fig. 1, the cas ing being shown insection. Fig. 3 is a transverse section through abearing-rin g. Figs.4:, 5, 6, 7, S, 9, and are side views, and Figs. l, 5, 6", 7, S, 9*, 10"are top views, respectively, showing different forms of eyepiece-prisms.Fig. 11 is a transverse section showing a side view of the halvingdevice as seen from the right-hand end of the instrument. Fig. 12 is anelevation thereof, looking toward the observer. Fig. 13 is a horizontalsection of the same. Fi 1a is a detail side elevation showing therocking lens-lever. Fig. 15 is a detail side elevation thereof. Fig. 10is a side elevation of our range-finder provided with a stand. Fig. 17is an end elevation thereof. Fig. 18 is a vertical transverse section ofthe same. Fig. 19 is a vertical longitudinal section thereof. Fig. 20 isan enlarged elevation of the coupling. Fig. 21 is a transverse sectionthereof. Fig. 22 is a diagrammatic view of the instrument. Fig. showspartial images in coincidence.

Fig. 24: shows partial images out of coincidence. Fig. 25 is a detailsection showing means for adjusting the scale on the prism-frame.

Figs. 1 and 2 show a range-finder embodying some of the improvements towhich this specification more especially refers.

A is the outer case of the instrument, composed of two tubes in themanner described below.

B B are respectively the upper and lower metal bars of the frameworkcarrying the principal optical parts of the instrument, especially thereflectors O G which are represented as made of speculum-metal, the objectglasses, contained in holders D D and the eyepiece-prisms,hereinafter described, contained in a box E. This framework consists oftwo metal bars ll B as stated, (preferably of copper, on account of itshigh conductivity for heat,) of the section shown in Fig. 3, or othersuitable section, connected together by a system of waved bracing F.This bracing F may consist of wires or rods, but we prefer to constructit of a strip or plate F, of copper or other metal, (preferably withthickened edges,) which is bent upward and downward in a waved line, asshown in Fig. 1, and soldered or riveted or otherwise attached to thebars 13 B This strip F is pierced with apertures F of the necessarydimensions to allow the passage of the beams of light (reflected,respectively, from the reflectors C 0 to the eyepiece-prisms. Thisbracing therefore constitutes a system of diaphragms, besides givingstrength to the frame.

\Ve may sometimes use a cast-metal frame of a construction somewhatsimilar to that above described. The essential feature of this frameworkis that the upper and lower bars being flat or nearly flat expose muchless surface than a tube would do to receive heat from the front or backof the instrument, and in the second place afford the best means for theconduction of the heat received. from the back to the front of theframework, or vice versa, thus tending to maintain the front and backportions of the frame or support carrying the optical parts of theinstrument or some of them as nearly as possible at the sametemperature. It is not essential that the upper and lower bars should beso nearly at one and the same temperature. The framework described has,then, the advantages over the tube hitherto customarily used forsupporting the optical parts, or some of them, of single-observerrange-finders or telemeters that it affords convenient access to thevarious parts during construction and subsequently, and that it greatlylessens the liability of the instrument to give erroneous indications,due to bending caused by unequal heating at the front and back of theinstrument. 7

The framework is supported from the outer case A of the instrument bymeans of two.

bearing rings or pieces G G one of which, G, is, as shown in thedrawings, constructed in a similar manner to the gimbal-ring of amariners compass. The other bearing-ring, G we prefer to construct asillustrated in Fig. The ring G which is fixed to the outer case byscrews or other means, carries three screwed plugs H H H containingconical or spherical recesses at their inner ends, and the instrument issupported by means of three pillars or struts I I I extending betweenthese conical or spherical recesses and similar recesses in partsattached to the framework B B The object of this special means ofsupport is that while the bearing G prevents the instrument from movinglongitudinally or transversely in the case or from rotating about theaxis of the case the bearing shown at G does not control the instrumentlongitudinally nor rotationally with refence to the case A, and thus anybending or twisting of the case A communicates no bending or twisting tothe tube or framework carrying the optical parts.

J J Fig. 2, are windows, preferably constructed of optically-parallelplane glass, which serve to exclude rain and dust from theinterior ofthe instrument. K is the frame, carrying the deflecting-prism; L, thescrew, operating that frame M is the scale; N, the right eyepiece; N theleft eyepiece.

O is a small object-glass which, together with a conical lens in theeyepiece N constitutes a small Galilean telescope, which we sometimesuse as a finder to enable the observer more quickly to direct theinstrument upon any given object, in the same manner as the finderfacilitates the use of an astronomical telescope. In this case theconcave lens in the eyepiece N above referred to, may only occupy onehalf of the aperture of the eyepiece, the other half having opposite toit a portion of a convex lens, by means of which a portion of the scaleand an index attached to the framework B B may be seen. The scale is,preferably, in this case kept above or below the level of the center ofthe instrument, so as not to interfere with the view of the object to beobserved through the 'finder. The screw by which the deflectingprism ismoved is worked by a pinion P, into the screw L (supported in bearingsattached to the framework B B by means of a connecting-piece providedwith universal joints and freedom for endwise motion, but capable ofcommunicating rotary motion in asimilar manner to that hereinafterdescribed with reference to the halving adjustment, so that no importantforces tending to bend the framework may be communicated to theframework from the hand of the observer.

In Figs. 4, at, 5, 5, (5, 6*, 7, 7, 8, 8, 9, 9 10, and 10 we showseveral methods of carrying out our improved system of constructing theoptical arrangements situated in the center of the instrument forreflecting the beams of light to the eye of the observer. Plane mirrorsmay in some cases be substituted for reflecting-prisms where suchmirrors would produce a like effect. These optical arrangements (whichin the instrument are contained or held in a case or holder E, shown inFigs. 1 and 2 and in more detail in Figs. 11, 12, and 13) we usuallydesignate eyepiece-prisms. Figs. 4 and 4. show one arrangement of sucheyepiece-prisms.

T is a prism of speculum-metal or other opaque reflecting material withan edge S as sharp as possible, which edge is situated in the focus ofalens or eyepiece N. This prism or its equivalent in other arrangementswe designate the separating-prism.

U U are two pieces of glass, each of which may be formed of two prismscemented together or of one piece having the form of such a combination.For convenience We shall call these reflectors prisms, even wh e11compound. These prisms U U receive upon their faces V V beams of lightfrom the two ends of the instrument, respectively, and reflect thesebeams through a right angle, or approximately so, onto the sloping facesWV V whence they are reflected through the faces m 00 onto theseparating-prism T, which again reflects them through the lens oreyepiece N. The several angles of these prisms may be somewhat modified,but we prefer to make the angle at S of the separating-prism ninetydegrees and the angles between the faces W X l/WX forty-five degrees.

Figs. 5 and 5 show an alternative arrangement in which thespeculum-metal separatingprism is replaced by a totally-reflectingprism,

'(or combination of two prisms T T The prism T is cemented to the prismT by means of Canada balsam or other transparent material of as nearlyas possible the same refractive index as glass.

Figs. 6 and 6 show another alternative arrangement in which theseparating-prism is equilateral, or nearly so. In this case the faces WV7 are parallel, respectively, to

the remote faces of the separating-prism T while the faces X J areparallel,or nearly so, to the near faces of the separating-prism T Figs.7 and '7 show another alternative arrangement. U U representright-angled prisms arranged to receive the beams of light from theobjective and to reflect them away from the eyepiece into the prism TThe faces IV X of the prism T' are at right angles to each other, andthe faces 7 X are at right angles to each other, while the angle betweenthe faces X is preferably a few degrees greater than one hundred andtwenty degreessay one hundred and twentyfive degreesin order to allowrays of light passing from the reflecting-face to points on thereflecting-face X (close to the edge S) to pass clear of the face X. Thepaths of two rays are shown in the drawings. In this case the faces Xand X must be silvered.

In another arrangement shown in Figs. 8 and 8 the separating-prism T isof speculummetal or other opaque reflecting material. The prisms U" Lreceive the beams of light on their faces V V and reflect them away fromthe eyepiece to the faces IV IV, which reflect them to the separatingprism T whence they are reflected to the eyepiece.

The arrangements shown in Figs. 7, 7*, 8, and 8 have the advantage thatthe object observed is caused to appear erect without the aid of anerecting system of lenses in the eyepiece.

In all the above cases it will be noted that there are three reflectorsfor each beam in the eyepiece-prism combination, two reflecting-surfacesbeing necessary in each of the beams to direct the light onto theseparating edge. In the next case, however, Figs. 9 and 9, two of thereflections are replaced by two refractions.

T represents a prism of glass whose section is a square or a rhomboid,(or approximately so,) through which the beams of light (afterreflection from the prisms U U are transmitted and refracted, as shown.In this case the edge of the prism nearest the eyepiece forms theseparating edge, and upon it the eyepiece is focused.

Figs] 0 and 10 show another arrangement of prisms in which the light isrefracted in passing through the inclined faces X X of the prisms U U Inthis case the prisms U U may be made of crown-glass, and prisms 7i Z offlint-glass, maybe cemented to those faces in order to constitute anachromatic arrangement. The images are, as in the other cases, formedabove and below the separating edge S of the separating-prism T thefaces of which have such an angle that the beams of light striking themin an inclined direction are caused to become parallel to one anotherbefore passing through the eyepiece.

In the eyepiece-prism arrangements shown in Figs. 5, 5, G, G, 7, 7, 10,and 10 the fieldlens of the eyepiece (or a single-lens eyepiece, if suchbe used) maybe cemented onto the outer surface of the separating-prisms,as shown; or the outer face may in some cases be ground convex, so as tobe equivalent thereto.

It is to be understood that the essential feature of our improved systemof eyepieceprisms is the use of a prism (which for distinction we callthe separating-prism) having one edge (which for distinction we call theseparating edge) parallelto the length of the instrumentand in the focusof the eyepiece, (or nearly so,) which prism is so formed and disposedthat the two images formed by light entering at the two ends of theinstrument, respectively, are formed at or near the edge referred to,and while the rays forming the images approach the separating edge indifferent directions they are respectively either refracted at orreflected by the two faces which meet in the separating edge, so as topass through the eyepiece as if they came from one image. The portion ofone image which falls below the separating edge and the portion of theother image which falls above that edge are not seen by the observer.

Figs. 11, 12, and 13 show our improved method of effecting the halvingadj ustment that is, to accomplish the condition that the two partialimages shall form a complete one, Fig. 11 being a side view of thearrangement as seen from the right-hand end of the instrument, Fig. 12an elevation looking toward the observer, and Fig. 13 a horizontalsection. The arrangement of eyepiece-prisms shown in these figures isthat shown in Figs. (3 and 6, but the method is applicable also to othersystems of eyepiece-prisms constructed upon our improved methodas, forexample, those shown in Figs. 4,4,5,5,8,8,10, and 10. The prisms U U areheld in a box m, fixed to the framework B" I3 while the separating-prismT is held in a metal piece a, to which are attached two plates 0, whichpass along the sides of the box on. These plates are connected at theend remote from 92. by means of a piece I. Another piece Qis fixedacross the back of the box at, and springs R tend to force P and Qapart, while they are pulled together by means of a screw (1,, actuatedby a worm-wheel Z), driven by a worm 0, so that when the worm is rotatedthe piece I is moved backward or forward, carrying with it the cheeks orplates 0 and the block a, and thus the separating-prism T is movedoutward or inward relatively to the prisms U U The effect of such motion(as will be obvious from the paths of the reflected rays, as shown inFig. 6) is to cause the two partial images of the objects observed, seenrespectively above and below the separating edge S, to appear to movevertically toward or from each other, by which means the adjustmentwhich we term halving is accomplished.

Apertu'res, as shown at d, are made in the sides of the box on and inthe checks 0, so

as to admit the beam of light from the two ends of the instrument to theprisms U U respectively.

The shaft 6, Figs. 12 and 13, is connected to a milled head f, Fig. 2,by means of a shaft 9, Figs. 1 and 2, preferably provided with couplingsh 7L2, so constructed that while they communicate rotary motion from theshaft carrying the milled head f they impart no important forces to theframe work B tending to bend the latter. Such couplings may convenientlybe constructed as follows, (see Figs. 20 and 21:) Short pieces ofcylindrical tubes g, having two longitudinal slots 9' diametricallyopposite each other, are fixed on the ends of the shaft g. The shaft 6and the spindle carrying the milled head f have each a spherical orsomewhat spherical end e, which lie within the tubes referred to, andpins 6', passing through these spherical ends, engage in the slots 9 ofthe tubes g", attached to g, and communicate rotational motion to thelatter, while exerting no important longitudinal or bending stresses.

In Figs. 1 and 2 the scale M is shown attached to a screw 2', whichpasses through a nut j, carried upon the prism-frame K, but free torevolve relatively thereto. Referring to Fig. 25, access to the nut maybe gained through an aperture a in the case A, provided with a removablecover a or the nut 7' may be formed as a toothed wheel j, gearing with apinion-rod supported from the framework B, driven by a milled headattached to the tube A and communicating its motion to the samepinion-rod through the medium of a shaft provided with couplings, in amanner similar to that above described with reference to the halvingadjustment.

Figs. 14 and 15 show one means of carrying out our improved method forthe observation of lights and other objects difficult to observe upon onaccount of their smallness of apparent dimensions or irregularity ofoutline.

70 are lenses or pieces of glass having one or both surfaces ground toeither a concave or convex cylindrical form, such as the lenses used byOpticians in spectacles to neutralize astigmatism, but we use lenses ofgreater curvature than ordinary spectaclelenses when we introduce themin the position indicated in the drawings. These lenses are fixed to arocking lever Z, which is pivoted upon the outer end of the screw a.(Shown in Fig. let.) The leveris kept in its position by means of acollar or other suitable device. This lever is omitted in Figs. 1, 2,11, 12, and 13 to avoid confusion. WVhen the lever is in the positionrepresented in Figs. 14 and 15, the beams of light coming to the prismsU U from the two ends of the instrument, respectively, pass through theastigmatizinglenses. The effect of interposing these lenses is to causethe images of a spot of light to appear as a line at right angles orapproximately, so to the separating edge S, before mentioned. When notrequired, the lenses may be removed from the beams of light by rotatingthe lever Z so as to bring the lenses 1070 into the positions indicatedby the dotted lines at 70, The lever Z is operated from the outside ofthe tube A by means of crank q, the pin 19 of which passes through aslot 25 in the lever Z in such a manner as not to apply forces tendingto bend the framework B B of the instrument.

The crank q is worked by means of a lever r, lying outside of the tubeA, as .shown in Figs. 15, 16, and 19, the crank q and the lever 0' beingfixed to a spindle passing through a suitable bearing carried by thetube A.

The screw to, Fig. 15, is for the purpose of stopping the lever Z, andconsequently the lenses 7a 7a", in the desired position. WVe do notconfine ourselves to this mechanism for putting the cylindrical lensesinto the paths of the beams, nor do we confine ourselves to introducingthe lenses into the position indicated in the drawings.

Lenses having one or both surfaces cylindrical may be introduced intothe beams of light at any point of the course ofthose beams. Thus theymay even be introduced outside of the windows, so that the beams passthrough them before entering the instrument, the lenses being chosen ofsuch a curvature as to produce the desired length of streak.

One lens may be introduced into the two beams of light after these havepassed the separating edge and either before or after the beams havepassed through the eyepiece or one lens of the eyepiece, but this hasthe disadvantage that the separating edge will no longer be clearlyvisible while the object is astigmatized.

In Figs. 1, 2, and 3 the outer case A is shown constructed of two tubes,one outside of the other. One or both of these tubes is preferablyconstructed of a metal having high 0011- ductivity for heat, such ascopper, in order to further equalize the temperature around theframe-piece or tube to which the optical parts are attached.

Figs. 16, '17, 18, and 19 show our improved arrangement of stand for theinstrument, suitable for use on board ship. 11 represents a pillar orpedestal constructed of metal or wood, carrying a vertical spike orpivot G. This pillar H" is fiXed to the deck or other portion of theship by suitable screws or other connections. A tank F is supported uponthe spike G, so as to be free to revolve in azimuth about the latter.This tank may conveniently be constructed of three castmetal plates, ofthe shape shown in outline in Fig. 17, which form its two ends and acentral diaphragm. A sheet of metal is bent .round these plates andfastened to them, thus forming the front, bottom, and back of the tank.The central diaphragm may contain a socket to fit over the spike G, andthe tank may have a flange or facing I, resting upon lIO a correspondingfacing attached to the pedestal H. Knife-edges E, fixed to the ends ofthe tank, support a framework 0, to which a balance-weight D isattached. This framework C also supports two forks or bearings B B Inthese bearings B," B, the instrument A rests, so as to be free to beturned about its longitudinal axis, while it may be prevented frommoving endwise by means of slightly-proj ecting flanges or collars,attached to the instrument and lying on each side of one of thebearings.

The instrument A may be secured in the bearings 13, D by means of hingedcoverpieces K, K fixed to the bearings by means of pins. Attached to theswinging frame a handle L", Figs. 10, 1'7, and 18, may be provided, mostconveniently placed at the lefthand side of the observer, when using theinstrument.

The tank may when desirable be partly filled with water or other liquid,as shown in Fig. 18.

During use the instrument may be turned in azimuth about the spike G andmay be rotated in thebearings B, 13, to the required angular altitude,but the latter motion may also be accomplished by swinging it upon theknife-edges E by aid of the handle L". Again, if the instrument is setby rotation in its bearings so as to be directed toward the horizon orother altitude the balance-weight 1) tends more or less to maintain thedirection of observation independently of the rolling or pitching of theship, while the tendency of the instrument to oscillate may be checkedvor damped by means of liquid in the tank, and the observer may furthercontrol such motions by use of the handle. The tank further serves,though no water be used in it, to shield the balance-weight from thewind, which otherwise would tend to move the instrument in altitude.

Bearings of the ordinary form or ball or roller bearings may besubstituted for the knife-edgesE; or, again, bearings equivalent to13,.ll, may be attached to the tank or an equivalentsupporting-frainework free to revolve in azimuth relatively to thepillar H, and the instrument A may be supported in such bearings andhave attached to it a balance-weight equivalent to the balance-weight D.In this case the handle L would be attached to the instrument A.

Fig. 22 is a diagrammatic representation of the instrument, detailsbeing omitted in order to render the mode of operation more easilyfollowed. Two beams of light from the objeet viewed are received byreflectors G C and transmitted through objectives D D toward the centerof the tube, where an arrangement of prisms E is placed. These prismsreflect the beams outward through the right eyepiece N. By these meanstwo partial images of a distant object are seen, one over the other, asshown in Fig. 2a.

The

image seen in the upper half of the field of view of the eyepiece N isthus formed by the equivalent of a telescope directed toward the objectfrom the righthand end of the instrument, the i.nage seen in the lowerhalf being formed by the equivalent of a second telescope looking at theobject from the lefthand end. Suppose a very distant object is viewed byrays shown at L U, Fig. 22, and that the partial images are seen incorrect coincidence, as illustrated in Fig. 23. If now the objectapproaches the instrument, the beam of light received at C will have aditlerent direction, such as is shown by the dotted line L and thepartial images will no longer appear in proper coincidence, but willoccupy such relative positions as are shown in Fig. 24. The partialimages might evidently be brought together by rotating the reflector C,but the necessary rotation would be almost infinitesimal, and wouldconsequently require to be made and indicated with excessive delicacy.

\Ve claim 1. A range-tinder or telemet-er comprising a framework, forsupporting the optical parts of the instrument consisting of twolongitudinal pieces, and a bracing by which the pieces are connectedtogether; substantially as de scribed.

2. A range-finder or telemeter comprising a framework, for supportingthe optical parts of the instrument consisting of two longitudinal barsand a strip provided with apertures and bent upward and downward andconnected with the bars to provide a bracing; substantially asdescribed.

A rangeiinder or telemeter comprising an eyepiece, a prism having oneedge situated in the focus of the eyepiece or nearly so and parallel tothe length of the instrument, and lenses; the prism being so arranged incombination with the lenses that the partial images of an object viewedthrough the instrument are formed respectively above and below the edge,while the beams forming these images meet in the edge referred to;substantially as described.

t. A range-finder or telemeter comprising a lense or lenses interposedinto one or both of the means of light by which an object is seen forthe purpose of drawing out or stigmatizing one or both of the images;substantially as described.

5. A range-finder or tclemeter comprising a framework for supporting theoptical parts, and a case composed of inner and outer tubes, havingapertures and connected together at their apertures, providing a spacebetween the tubes, for the purpose of retarding and rendering uniformthe communication of heat to and from the inner tube and framework;substantially as described.

6. A range-finder or telemeter comprising a case composed of inner andouter tubes, a framework, for supporting the optical parts,

a bearing-ring for supporting one end of the names to this specificationin the presence of framework, and a bearing for the other end twoWitnesses. of the framework consisting of a bearing-ring having threescrew-threaded and recessed 5 plugs, and three pillars occupyingcorrespondingly recessed portions in the framework; Witnesses:substantially as described. JOHN SIDDLE,

In testimony whereof we have signed our ARTHUR HARTLEY YUILE.

ARCHIBALD BARR. VILLIAM STROUD.

